Companion. Protector. Killer.
http://www.imdb.com/title/tt0107504/
A genetically mutated dog is accidentally released from the lab of Dr. Jarret and ends up at the home of news reporter/animal rights advocate Lori Tanner. The dog, Max, endowed with intelligence and other special abilities, is at first lovable, but also proves to be a ferocious, unstoppable killer.